The aims of this project are to study the structure and biosynthesis of lipids, lipopolysaccharides and polysaccharides of mycobacterium species, and to investigate the structure and immunochemistry of the yeast cell wall mannans. The two parts are related since mycosis often accompanies tuberculosis, and immunochemical cross-reaction is often observed between mycobacteria and yeasts. The studies on mycobacterial products will deal with the location of the different kinds of acyl groups in the methylglucose lipopolysaccharide and with the mechanism of the methylation of the polysaccharide. We will also study the methylation of the methylmannose polysaccharide and attempt to learn something about the relationship between this substance and the above lipopolysaccharide. The mechanism of acylation and the processes which control the degree and type of acylation will be investigated. The structure of yeast mannans and their organization in the cell wall will be investigated. We hope to define the pathway for the biosynthesis of the mannans and the control mechanism by which the species-specific structures are built up. By use of mutants and hybrids of haploid strains with different mannans, we expect to be able to map the genes which are involved in these processes.